Iron-Deficiency Anemia: Symptoms, Causes, Tests (Ferritin), Treatment, and Diet

Iron is essential for making hemoglobin, the protein in red blood cells that carries oxygen throughout the body. When iron levels are too low, the body can't produce enough healthy red blood cells, resulting in iron-deficiency anemia — the most common type of anemia and one of the most common nutritional deficiencies worldwide.

Common causes include inadequate dietary iron intake, poor iron absorption, and blood loss — whether from heavy menstrual periods, pregnancy, or, less commonly, gastrointestinal bleeding. Women of childbearing age are particularly at risk because of monthly blood loss combined with the increased iron needs of pregnancy.

The symptoms of iron-deficiency anemia can develop gradually and are often mistaken for general tiredness: fatigue, pale skin, shortness of breath on exertion, dizziness, and brittle nails are all common. Because these symptoms overlap with many other conditions, a blood test — typically a complete blood count along with iron studies and ferritin — is needed to confirm the diagnosis.

Because other causes of anemia — such as thalassemia trait — can look similar to iron deficiency on a routine blood count but need a different approach, it's important to confirm the diagnosis with a blood test before starting iron supplements rather than taking them on a hunch. Once iron deficiency is confirmed, treatment usually starts with iron supplementation, taken as prescribed, along with dietary changes to include more iron-rich foods such as red meat, legumes, and leafy greens (ideally alongside vitamin C, which improves iron absorption). It's also important to identify and address the underlying cause of the deficiency, especially if blood loss is involved — supplements alone won't fix a problem that keeps recurring. This is especially important for men and for women past menopause, since they don't have an obvious explanation like menstrual blood loss — new or unexplained iron-deficiency anemia in these groups should prompt a doctor to check for a source of bleeding in the digestive tract.

Most cases of iron-deficiency anemia respond well to treatment within a few weeks to months, though it may take longer to fully rebuild the body's iron stores. If you're experiencing persistent fatigue, pale skin, or other symptoms described above, a simple blood test can confirm whether iron deficiency is the cause — always discuss your results and treatment plan with a doctor.

Symptoms: Common and Less Obvious

These are the NHS's lists; none is specific to iron deficiency, so testing matters.

Tests: CBC and Ferritin

A complete blood count shows whether you are anemic and whether the red cells are small; iron studies and ferritin show the body's iron stores. No special preparation is needed for a blood count. If no cause is obvious, your doctor may look for hidden bleeding, for example with a stool test, and may refer you to a gastroenterologist. WHO estimates that in 2019 about 30% of non-pregnant women and 37% of pregnant women aged 15–49 worldwide had anemia and that iron deficiency is the most common nutritional cause. Thalassemia trait can look similar on a count, so confirm before treating — see premarital screening in Jordan.

Iron Tablets: What to Expect

• Treatment with iron tablets usually lasts about six months according to the NHS, so that stores are rebuilt after the hemoglobin recovers.
• Taking tablets with food and a glass of orange juice can reduce upset and help absorption; do not stop because of mild side effects.
• Common side effects: constipation, diarrhea, stomach pain, heartburn, nausea and dark stools. See our constipation guide.
• Repeat blood tests after a few months show whether levels are recovering.
• Keep iron tablets away from children — an overdose is dangerous.

Diet: What Helps and What Hinders Absorption

More iron-rich foods (meat, legumes, dark-green leafy vegetables, dried fruit, fortified cereals or bread) help; pairing with vitamin C helps. Large amounts of tea, coffee, dairy and foods high in phytates (for example whole-grain bran) can make it harder to absorb iron, so keep them apart from iron-rich meals and tablets. Diet alone rarely corrects a true deficiency — treatment comes from your doctor.

Special Groups

• Women with heavy periods and pregnancy: the most common causes; ask about your period pattern and pregnancy care. WHO notes anemia in pregnancy is linked to preterm birth and low birth weight.
• Men and women after menopause: new iron deficiency needs a search for a source of bleeding.
• Children and adolescents: poor growth or school tiredness need a pediatric assessment — do not give adult iron products.
• People taking NSAIDs or having ulcers: stomach bleeding can cause iron deficiency.

Sources

• Iron deficiency anaemia — NHS
• Anaemia — WHO fact sheet